Appropriate Sibling Relationships
by dicaeopolis
Summary: When Mama Matsuoka's away, her children will play. Rin is a little flustered about this. Especially since Gou has taken a fancy to wearing his jacket. RinGou, warning for incest.


Right. Okay. This was normal sibling behavior. Rin had missed a lot of Gou's formative years when he was in Australia. It was understandable that he would've forgotten how sibling relationships worked. This was what siblings did.

Rin slumped down the wall of the hallway and buried his burning face in his hands.

This was not what siblings did.

He'd only wanted a pair of jeans to wear during chores. His mother was on a week-long trip that coincided with a spring break he'd otherwise be spending at Samezuka, and by Wednesday, he and Gou had managed to pile up dishes in the sink higher than his sister's head. But when he went into his childhood bedroom to dig through his bureau for the pants he had left there when he started at Samezuka, the drawer was curiously empty.

"Gou," Rin had called out, knowing that her bed was only on the other side of the wall from his, "do you know where my jeans are?"

"I don't know," came the muffled reply. "Maybe you left them at school."

"I don't wear jeans at school!" He shut the drawer and went into the hallway, poking his head into his sister's room. "Did Mom ever - Gou!"

Not just his jeans, but his jacket. She was curled up on her bed, looking anything but guilty, surrounded by homework papers and clad in Rin's baggy jeans and black Samezuka jacket. Her feet were almost entirely covered by the length of the pants, and, lying on her side, the jacket had ridden up her hip to reveal the slightest strip of lace and creamy skin above the denim waistband.

Gou blinked owlishly at him. "What?" She brushed a strand of cherry-red hair out of her face. The sleeve covered nearly all of her hand.

With a start, Rin realized he was staring and coughed to cover his embarrassment. "Why are you wearing my jeans?" he asked, voice less irritated than it should've been and more shaken.

Gou's eyes flashed towards the floor, and Rin followed her gaze to see no less than three pairs of jeans that clearly didn't belong to his petite sister crumpled on the floor. He scowled at her and moved to gather them up.

"They're mine, just cause I'm not living here doesn't mean-"

"But onii-chan, they're more comfortable," she protested.

"Can't you buy your own?"

"It reminds me of you," she replied, eyes wide and voice innocent.

Rin had turned tomato-red and slammed her door on the way out.

Rin let out a long breath, stood up, and went to change into his newly acquired jeans for chores. But not even the pile of dishes could distract him from Gou's fashion choices.

At least it was his jacket. Things could've been worse. It could've been Seijuurou's. It could've belonged to some guy who would have lewd...fantasies...about...her…

A plate slipped out of Rin's hand and smashed to pieces on the floor. He groaned aloud.

That night, he couldn't fall asleep, tossing and turning. Gou had looked cute in his jacket - very cute, in a way that he should not be finding his own sister cute.

It was okay to acknowledge aesthetic attraction, right? Gou was an attractive girl. He hadn't spent much time around her since they were little, and that was why he was noticing now. Of course. This was perfectly natural.

Rin was reaching for his iPod to tune out his thoughts when a squeak sounded through the wall.

He froze. Horrible thoughts ran through his mind - robbers, rapists, home invasion. He was halfway to the door and grabbing his hairbrush for a makeshift weapon when a louder noise sounded - one that, as a boarding school student, he couldn't help but recognize.

Gou let out a long, breathy moan, mumbling something at the end that he didn't catch.

Rin stood rooted to the floor, cheeks lit up like fireworks. Through the thin wall, Gou sighed, and her bed creaked. There were no more noises, but it took him a good while to be able to move back to his bed.

He didn't stop blushing for an hour, and didn't fall asleep for two more.

Oh, he was going to hell. Straight down.

The next morning, things were only a little easier to put out of his mind. Rin padded into the kitchen, shoved bread in the toaster for himself and pulled out the cornflakes for his sister, and went to wake her up.

He opened the door of her room. "Hey, Gou, breakfast is almost read-"

Gou was sprawled out on her back, arms thrown above her head. Her blanket was in a tangle at the foot of her bed, and her sheet, which didn't hide much in the first place, was draped low enough across her hips that the v drew his eyes downwards. The jacket was unzipped across her chest, and her cleavage was…

Rin couldn't think of any word besides tantalizing.

Gou murmured in her sleep and shifted. The black fabric began to slide off her torso.

Rin tripped twice on the way to the door, nearly slammed it behind him, and knocked loudly several times instead.

And it didn't help in the slightest that she showed up at breakfast in tiny satin sleep shorts and his damn jacket again, and it was only zipped about two-thirds of the way up and dear lord was she wearing anything under that?

As they began eating, Rin realized something awful.

Gou hadn't moved after she...uh...after what he had heard last night. And when he woke her up, his jacket and a thin piece of linen had been the only things protecting her modesty.

So...when she was...had she been...in his jacket?

Oh no.

Rin had to put a stop to this - for both of their sakes.

He cleared his throat. "So, um."

Gou paused in her meal to glance at him, eyebrows lifting in surprise when she saw his face. "Onii-chan, you're blushing."

Fuck, he was blushing. The realization only made him redder, but he kept his eyes fixed upon his toast, determined to ask her about what he had heard. "You were...pretty, uh, loud last night."

And now Gou was flushing too, spoon halfway to her mouth, eyes wide, and mouth in a perfect o. "I…"

"It's okay," he interrupted her, feeling the heat in his face spread to his neck and ears. "I mean - you're a teenager, it's normal-"

"I thought you slept with your iPod on-"

"Seriously, Gou, I don't want to talk about it, it's just that I came in to wake you up this morning and I noticed that you were wearing my jacket and…I...uh…" Gou looked absolutely mortified, but Rin plowed on. "Noticed that...er...your pajamas must all be in the wash?"

After a brief pause, Gou opened her mouth, but Rin interrupted again, completely scarlet by now. "I just...would rather you not be wearing my clothes when you're doing that sort of-"

Gou cut him off. "I told you yesterday why I like wearing this jacket."

Rin tilted his head in confusion. "Because it's more comfortable?" She shook her head, and he dug through his memory for what she had said next.

And suddenly, he remembered.

It reminds me of you, she had said.

Gou looked up, and red met red - one set of eyes wide and flustered, and the other...mischievous.

Rin couldn't even get out a halfhearted protest before she was pulling him back into her bedroom.


End file.
